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A compact and unambiguous way to describe a font in CSS.
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Font Variation Description

A way to unambiguously, compactly and clearly describe a set of @font-face properties. This is implemented as a simple string. For example


This specification is currently focused on describing an existing @font-face descriptor, rather than describing an intended descriptor. The latter becomes more complicated when considering unspecified properties and the existence or non-existence of a particular font face.


The order of properties is well defined. Currently:


Forward compatibility is maintained by adding new properties to the end. Possible additions:



The possible values for each property are well defined, and a value is required for each property. Values must be a single character. The Font Values Description value and its equivalent CSS value for each property are as follows.

Each property must have a default value, but may have aliases for use when generating a Font Values Description. To maintain unambiguous output, there must be no alias return values.


n: normal  (default)
i: italic
o: oblique


1: 100
2: 200
3: 300
4: 400 (default, also recognized as 'normal')
5: 500
6: 600
7: 700 (also recognized as 'bold')
8: 800
9: 900


a: ultra-condensed
b: extra-condensed
c: condensed
d: semi-condensed
n: normal          (default)
e: semi-expanded
f: expanded
g: extra-expanded
h: ultra-expanded

font-variant (not currently in the CSS3 font spec)

n: normal
c: small-caps

Parsing Rules

See compaction test suite and the expansion test suite for a complete set of rules.


(no properties)
=> n4

font-style: italic;
=> i4

font-weight: normal;
=> n4

font-weight: bold;
=> n7

font-style: normal;
font-weight: 400;
=> n4

font-style: italic;
font-weight: 500;
=> i5

A CSS class name for a single font


Describing an entire family of fonts. Here each variation is delimited by a comma.

"Droid Serif:n4,i4,n7,i7"

This string describes four fonts in the family 'Droid Serif':
- Normal
- Italic
- Bold
- Bold Italic
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